In advance of the release of thousands of e-mails from Sarah Palin’s time as governor, we take a look at some of the issues that marked her tenure.

The specter of excessive influence by Big Oil has been Sarah Palin’s chief political target and godsend for years, a populist theme ideally suited to a state that gets four-fifths of its revenues from that industry. But it has also attracted independent-minded voters who feel that powerful interests have skewed policymaking against them.

In Palin’s first statewide job, as chairman of an energy industry regulatory group, she helped blow the whistle on improper ties between several private firms and a fellow commissioner who was then — and still is — head of the state Republican Party. The resulting attention helped propel her toward the governor’s office, where one of her signal legislative achievements was to raise the oil industry’s gross tax rate, winning wide public support while bucking longstanding party orthodoxy.

Palin was close to others who worked in the energy industry: Her lieutenant governor, Sean Parnell, was previously a lobbyist for ConocoPhillips; he succeeded her when she resigned in July 2009 and he was elected in 2010 to a full four-year gubernatorial term. Palin’s appointee as head of the natural resources division, Marty Rutherford, was a former lobbyist for a subsidiary of the oil pipeline company TransCanada.

At the center of Palin’s claim to have been a champion of energy development while serving as governor was a legislative and political battle in which she chose TransCanada to build a 1,700-mile pipeline to carry natural gas from isolated fields to ports and other pipelines — a project currently estimated to cost $20 billion to $40 billion, to which Palin and the Alaska legislature committed $500 million in seed money.

In picking TransCanada, Palin rejected a deal her predecessor had signed with ExxonMobil, ConocoPhillips and BP, saying that Exxon should not let the screen door hit it on the way out. But those firms have not yet committed to shipping the gas — from land they control — through the not-yet-started TransCanada pipeline. And the discovery of new shale oil deposits elsewhere in the country has raised new uncertainty about the project’s feasibility.